US20040082782A1 - Method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid - Google Patents
Method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid Download PDFInfo
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- US20040082782A1 US20040082782A1 US10/303,784 US30378402A US2004082782A1 US 20040082782 A1 US20040082782 A1 US 20040082782A1 US 30378402 A US30378402 A US 30378402A US 2004082782 A1 US2004082782 A1 US 2004082782A1
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- Prior art keywords
- pentaerythritol
- phosphoric acid
- solvent
- bis
- reaction
- Prior art date
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- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims abstract description 39
- 150000007974 melamines Chemical class 0.000 title claims abstract description 15
- 238000000034 method Methods 0.000 title claims description 26
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 claims abstract description 63
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000000203 mixture Substances 0.000 claims abstract description 18
- 238000000498 ball milling Methods 0.000 claims abstract description 13
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 10
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229920000877 Melamine resin Polymers 0.000 claims abstract description 9
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 8
- 239000003054 catalyst Substances 0.000 claims abstract description 7
- 150000004996 alkyl benzenes Chemical class 0.000 claims abstract description 5
- 229910001507 metal halide Inorganic materials 0.000 claims abstract description 5
- 150000005309 metal halides Chemical class 0.000 claims abstract description 5
- 125000006527 (C1-C5) alkyl group Chemical group 0.000 claims abstract 2
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 46
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Natural products CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 33
- 239000002904 solvent Substances 0.000 claims description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 238000009835 boiling Methods 0.000 claims description 7
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical group [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims 1
- 125000003944 tolyl group Chemical group 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 36
- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 description 10
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 230000035484 reaction time Effects 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 229910019213 POCl3 Inorganic materials 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- UCQFCFPECQILOL-UHFFFAOYSA-N diethyl hydrogen phosphate Chemical compound CCOP(O)(=O)OCC UCQFCFPECQILOL-UHFFFAOYSA-N 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 3
- 229910019142 PO4 Inorganic materials 0.000 description 3
- 238000013019 agitation Methods 0.000 description 3
- 239000007810 chemical reaction solvent Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000001394 phosphorus-31 nuclear magnetic resonance spectrum Methods 0.000 description 3
- YASRHLDAFCMIPB-UHFFFAOYSA-N (1-oxo-2,6,7-trioxa-1$l^{5}-phosphabicyclo[2.2.2]octan-4-yl)methanol Chemical compound C1OP2(=O)OCC1(CO)CO2 YASRHLDAFCMIPB-UHFFFAOYSA-N 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 2
- NGNBDVOYPDDBFK-UHFFFAOYSA-N 2-[2,4-di(pentan-2-yl)phenoxy]acetyl chloride Chemical compound CCCC(C)C1=CC=C(OCC(Cl)=O)C(C(C)CCC)=C1 NGNBDVOYPDDBFK-UHFFFAOYSA-N 0.000 description 2
- OHRVBDRGLIWLPA-UHFFFAOYSA-N [3-hydroxy-2,2-bis(hydroxymethyl)propyl] dihydrogen phosphate Chemical compound OCC(CO)(CO)COP(O)(O)=O OHRVBDRGLIWLPA-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- SNVLJLYUUXKWOJ-UHFFFAOYSA-N methylidenecarbene Chemical compound C=[C] SNVLJLYUUXKWOJ-UHFFFAOYSA-N 0.000 description 2
- -1 primary amine salt Chemical class 0.000 description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- KCZIUKYAJJEIQG-UHFFFAOYSA-N 1,3,5-triazin-2-amine Chemical class NC1=NC=NC=N1 KCZIUKYAJJEIQG-UHFFFAOYSA-N 0.000 description 1
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- 238000004679 31P NMR spectroscopy Methods 0.000 description 1
- GCYLQCRCUDAZQG-UHFFFAOYSA-N C.C.C[PH](=O)OCC12COP(=O)(OC1)OC2.O=[PH](O)OCC12COP(=O)(OC1)OC2.OCC(CO)(CO)CO Chemical compound C.C.C[PH](=O)OCC12COP(=O)(OC1)OC2.O=[PH](O)OCC12COP(=O)(OC1)OC2.OCC(CO)(CO)CO GCYLQCRCUDAZQG-UHFFFAOYSA-N 0.000 description 1
- MVBYVBBYKGGYCC-UHFFFAOYSA-N C=P12OCC(CO)(CO1)CO2.O=P(Cl)(Cl)Cl.O=P12OCC(CO)(CO1)CO2 Chemical compound C=P12OCC(CO)(CO1)CO2.O=P(Cl)(Cl)Cl.O=P12OCC(CO)(CO1)CO2 MVBYVBBYKGGYCC-UHFFFAOYSA-N 0.000 description 1
- BKSBASLRXIHLEZ-UHFFFAOYSA-N CC1=NC(C)=NC([OH2+])=N1.O=[PH]([O-])OCC12COP(=O)(OC1)OC2 Chemical compound CC1=NC(C)=NC([OH2+])=N1.O=[PH]([O-])OCC12COP(=O)(OC1)OC2 BKSBASLRXIHLEZ-UHFFFAOYSA-N 0.000 description 1
- UEZVMMHDMIWARA-UHFFFAOYSA-N Metaphosphoric acid Chemical compound OP(=O)=O UEZVMMHDMIWARA-UHFFFAOYSA-N 0.000 description 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 description 1
- BDZBKCUKTQZUTL-UHFFFAOYSA-N triethyl phosphite Chemical compound CCOP(OCC)OCC BDZBKCUKTQZUTL-UHFFFAOYSA-N 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/40—Nitrogen atoms
- C07D251/54—Three nitrogen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
- C07F9/02—Phosphorus compounds
- C07F9/547—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
- C07F9/6564—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms
- C07F9/6571—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms
- C07F9/6574—Esters of oxyacids of phosphorus
- C07F9/65748—Esters of oxyacids of phosphorus the cyclic phosphorus atom belonging to more than one ring system
Definitions
- U.S. Pat. No. 4,454,064 discloses a method for preparing pentaerythritol phosphate, which comprises reacting pentaerythritol with POCl 3 in dioxane solvent at 75-125° C.
- the pentaerythritol phosphate thus prepared can be used as an intermediate for synthesizing a polyurethane flame retardant and a plasticizer.
- This preparation method will also generate HCl gas and a residual solution of excessive POCl 3 .
- U.S. Pat. No. 4,478,998 discloses a synthesis of an amino-s-triazine salt of a phosphoric acid having the following formula:
- said salt is melamine salt of bis-(pentaerythritol phosphate) phosphoric acid.
- the synthesized amino salt can be used as a flame retardant additive for certain polymer compositions.
- melamine reacts with acid chloride of bis-(pentaerythritol phosphate) phosphoric acid in water to obtain said melamine salt.
- Said acid chloride of bis-(pentaerythritol phosphate) phosphoric acid is synthesized through the following reaction formula:
- the present invention provides a method for preparing a melamine salt of bis-(pentaerythritol phosphate) phosphoric acid, which comprises preparing bis-(pentaerythritol phosphate) phosphoric acid, and reacting melamine with the obtained bis-(pentaerythritol phosphate) phosphoric acid to form a melamine salt thereof.
- the preparation of bis-(pentaerythritol phosphate) phosphoric acid according to the present invention has the following characteristics:
- the method uses P 2 O 5 as a reactant.
- the method uses a mechanochemical synthesis and uses a ball mill as a reactor.
- the method uses an alkyl benzene, such as toluene or xylene, as a solvent.
- the alkyl benzene may have one or two identical or different alkyls having 1 to 5 carbons.
- the solvent used in the method is at room temperature or pre-heated to 50-150° C.
- MX 2 metal halide
- the weight ratio of the catalyst to pentaerythritol is 1:99 to 5:95.
- the present invention has the following three advantages: (a) no generation of waste gas of HCl; (b) free of a waste aqueous solution generated from neutralization of HCl waste gas; and (c) avoiding handling of a residue solution containing unreacted POCl 3 .
- the reaction between melamine and bis-(pentaerythritol phosphate) phosphoric acid according to the present invention can be carried out in a ball mill or a conventional mechanical agitation reactor, which comprises ball-milling or mechanically mixing a mixture of melamine, bis-(pentaerythritol phosphate) phosphoric acid, and a solvent at room temperature to 100° C.
- Suitable solvents include (but not limited to) water, acetonitrile (CH 3 CN), and a mixture of the solvent used in the preparation of bis-(pentaerythritol phosphate) phosphoric acid with acetonitrile.
- said solvent is pre-heated to 50-100° C.
- said solvent is a mixture of toluene with acenonitrile preheated to 50-80° C., acetonitrile that has been pre-heated to 80° C. or boiling water, most preferably is boiling water.
- the present invention discloses a method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid, which comprises preparing bis-(pentaerythritol phosphate) phosphoric acid, and reacting melamine with the obtained bis-(pentaerythritol phosphate) phosphoric acid to form a melamine salt thereof.
- a method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid which comprises preparing bis-(pentaerythritol phosphate) phosphoric acid, and reacting melamine with the obtained bis-(pentaerythritol phosphate) phosphoric acid to form a melamine salt thereof.
- the molecular structure unit of phosphorus pentoxide is P 4 O 10 , usually represented by P 2 O 5 .
- Phosphorus pentoxide is a very strong dehydration agent, and is liable to react with water to form phosphoric acid.
- Pentaerythritol can be dissolved in diethyl phosphate solvent, therefore, after addition of P 2 O 5 , the reaction can take place at a reaction temperature of 90° C. While not dissolving in toluene, pentaerythritol will turn into a molten state when the temperature rises to 90° C. and can react with P 2 O 5 . Since pentaerythritol in its molten state has an extremely high viscosity and is difficult to agitate, the reaction yield is not high. Therefore, how to achieve an ideal agitation for pentaerythritol to have a sufficient contact with P 2 O 5 is a key factor in increasing the yield.
- Pentaerythritol does not dissolve at the boiling point of n-hexane at 68° C. and has no change in state at this temperature, this could be a reason why it does not react with P 2 O 5 in n-hexane.
- Pentaerythritol does not react with P 2 O 5 in toluene solvent at a temperature lower than 70° C. under traditional stirring process. When the temperature increases to 90° C., pentaerythritol can undergo a phosphate esterification reaction. The reaction time is about 10 hours. When the temperature rises to 105° C., the reaction time can be reduced to 6 hours.
- reaction yield and purity can be increased when, prior to the reaction, pentaerythritol is ground in toluene in a ball mill.
- the key factors affecting the method of the present invention include: heating of the solvent, material with a fine particle size, and complete mixing in the reaction. Therefore, a ball mill is considered as a reactor to achieve a complete grinding, mixing and thermal insulation in the reaction. A suitable reaction time is 4-20 hours.
- the reaction between melamine and bis-(pentaerythritol phosphate) phosphoric acid according to the present invention can be carried out in said ball mill or a conventional mechanical agitation reactor, preferably in a ball mill.
- the reaction can be carried out using acetonitrile or water as the solvent.
- the reaction can be completed in 6 hours by reflux.
- the reaction time is 7.5 hours.
- the obtained melamine salt of bis-(pentaerythritol phosphate) phosphoric acid has a good heat resistance, only about 10 ⁇ 20% of which will be decomposed at 200 ⁇ 300° C., and about 40% of which will remain at a temperature exceeding 600° C.
- the present invention uses P 2 O 5 to replace POCl 3 , and a mechanochemical synthesis process to overcome lack of a suitable solvent.
- the present invention has the following advantages: no formation of hydrochloric acid, no waste solution, environmentally friendly, without the need of heating in the reaction, high yield, increased purity, and capability of recycling solvent.
- a ball mill reactor with one liter capacity was used and ceramic balls with a diameter of 2 cm were used.
- Example 1 The product mixture of Example 1 was retained in the ball mill reactor, after the liquid portion was poured out. 21 g (0.166 mol) of melamine was poured into the ball mill, and 300 ml of acetonitrile which was pre-heated to 80° C. was added. The ball mill reactor was closed and rotated for 6 hours. 31 P-NMR spectrum of a sample of the reaction solution taken from the ball mill reactor showed no existence of 31 p peak, which indicated that b-PEPAP and phosphoric acid were all consumed. The product b-PEPAP.MEL and the by-product melamine salt of phosphoric acid were all insoluble in acetonitrile solvent. The reaction was completed with a conversion rate of 100%.
- Example 2 The procedures in Example 2 were repeated except that the liquid portion of the reaction mixture in the ball mill reactor was not poured out, 100 ml of acetonitrile which was pre-heated to 80° C. was added instead of 300 ml, and the ball mill reactor was for 7.5 hours. The conversion rate was 100%.
- Example 2 The procedures in Example 2 were repeated except that 350 ml of pre-heated boiling water was added instead of acetonitrile, and the ball mill reactor was rotated for 15 minutes only. 31 P-NMR spectrum of a sample of the reaction solution taken from the ball mill reactor showed no existence of 31 P peak. The reaction was completed with a conversion rate of 100%.
- the melamine salt of bis-(pentaerythritol phosphate) phosphoric acid obtained in Example 2 to Example 4 had an average particle size of 6-8 ⁇ m, and the particle size distributions thereof showed that 91% of the particles were smaller than 14.4 ⁇ m.
- Their IR spectrums were substantially the same and contained the following major characteristic absorption wavelength:
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Bis-(pentaerythritol phosphate) phosphoric acid is prepared by mechanochemical synthesis including ball milling a mixture containing P2O5, pentaerythritol, an alkyl benzene having one or two C1-C5 alkyl groups, and a metal halide catalyst, in a ball mill as a reactor and at a temperature of room temperature to 150° C. Melamine is then reacted with the resulting bis-(pentaerythritol phosphate) phosphoric acid to form a product of melamine salt thereof.
Description
- U.S. Pat. No. 4,454,064 discloses a method for preparing pentaerythritol phosphate, which comprises reacting pentaerythritol with POCl 3 in dioxane solvent at 75-125° C. The pentaerythritol phosphate thus prepared can be used as an intermediate for synthesizing a polyurethane flame retardant and a plasticizer. This preparation method will also generate HCl gas and a residual solution of excessive POCl3.
- U.S. Pat. No. 4,478,998 discloses a synthesis of an amino-s-triazine salt of a phosphoric acid having the following formula:
- when X and X′ in the formula are amino, said salt is melamine salt of bis-(pentaerythritol phosphate) phosphoric acid. The synthesized amino salt can be used as a flame retardant additive for certain polymer compositions. In Example 1 of said patent, melamine reacts with acid chloride of bis-(pentaerythritol phosphate) phosphoric acid in water to obtain said melamine salt. Said acid chloride of bis-(pentaerythritol phosphate) phosphoric acid is synthesized through the following reaction formula:
- HCl gas and a residual solution of excessive POCl 3 will also be generated in the abovementioned reaction.
- The present invention provides a method for preparing a melamine salt of bis-(pentaerythritol phosphate) phosphoric acid, which comprises preparing bis-(pentaerythritol phosphate) phosphoric acid, and reacting melamine with the obtained bis-(pentaerythritol phosphate) phosphoric acid to form a melamine salt thereof. The preparation of bis-(pentaerythritol phosphate) phosphoric acid according to the present invention has the following characteristics:
- 1. The method uses P 2O5 as a reactant.
- 2. The method uses a mechanochemical synthesis and uses a ball mill as a reactor.
- 3. The method uses an alkyl benzene, such as toluene or xylene, as a solvent. The alkyl benzene may have one or two identical or different alkyls having 1 to 5 carbons.
- 4. The solvent used in the method is at room temperature or pre-heated to 50-150° C.
- 5. The method uses metal halide MX 2, such as MgCl2 etc., as a catalyst, wherein M=Mg, Zn, or Al; and X=Cl, or Br. The weight ratio of the catalyst to pentaerythritol is 1:99 to 5:95.
- Compared to the conventional process, the present invention has the following three advantages: (a) no generation of waste gas of HCl; (b) free of a waste aqueous solution generated from neutralization of HCl waste gas; and (c) avoiding handling of a residue solution containing unreacted POCl 3.
- The reaction between melamine and bis-(pentaerythritol phosphate) phosphoric acid according to the present invention can be carried out in a ball mill or a conventional mechanical agitation reactor, which comprises ball-milling or mechanically mixing a mixture of melamine, bis-(pentaerythritol phosphate) phosphoric acid, and a solvent at room temperature to 100° C. Suitable solvents include (but not limited to) water, acetonitrile (CH 3CN), and a mixture of the solvent used in the preparation of bis-(pentaerythritol phosphate) phosphoric acid with acetonitrile. Preferably, said solvent is pre-heated to 50-100° C. and thus there is no heating while ball milling said mixture. More preferably, said solvent is a mixture of toluene with acenonitrile preheated to 50-80° C., acetonitrile that has been pre-heated to 80° C. or boiling water, most preferably is boiling water.
- The present invention discloses a method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid, which comprises preparing bis-(pentaerythritol phosphate) phosphoric acid, and reacting melamine with the obtained bis-(pentaerythritol phosphate) phosphoric acid to form a melamine salt thereof. Several factors affecting the synthesis of said bis-(pentaerythritol phosphate) phosphoric acid are discussed in the following:
- 1. Study on the Reaction Solvent
- The molecular structure unit of phosphorus pentoxide is P 4O10, usually represented by P2O5. Phosphorus pentoxide is a very strong dehydration agent, and is liable to react with water to form phosphoric acid.
- P2O5+3H2O→2H3PO4
- Furthermore, it can grab H 2O from reactant molecules to form metaphosphoric acid and related inorganic or organic material, e.g.
- P2O5+H2SO4→SO3+4HPO3
- P4O10+H2N—C(O)—C(O)—NH2→NC—CN+4HPO3
- P2O5+CH2═C(CH3)—C(O)—OH+CH3OH→CH2═C(CH3)—C(O)OCH3+2HPO3
- P 2O5 reacts with ethyl ether to form triethyl phosphate:
- P2O5+3(C2H5)2O→2(C2H5O)3P═O
- The strong reactivity of phosphorus pentoxide makes the selection of the reaction solvent greatly restricted. The inventors of the present invention have tried using a solvent such as n-hexane, diethyl phosphate, and toluene, etc. for performing the reaction, in which the reaction of using n-hexane as a solvent is not ideal and has an extremely low yield. When diethyl phosphate is used as a solvent, the reaction has a very good yield. However, since the properties of diethyl phosphate are too close to the properties of the product bis-(pentaerythritol phosphate) phosphoric acid, they are difficult to be separated. Therefore, toluene is selected as a reaction solvent.
- Pentaerythritol can be dissolved in diethyl phosphate solvent, therefore, after addition of P 2O5, the reaction can take place at a reaction temperature of 90° C. While not dissolving in toluene, pentaerythritol will turn into a molten state when the temperature rises to 90° C. and can react with P2O5. Since pentaerythritol in its molten state has an extremely high viscosity and is difficult to agitate, the reaction yield is not high. Therefore, how to achieve an ideal agitation for pentaerythritol to have a sufficient contact with P2O5 is a key factor in increasing the yield. Pentaerythritol does not dissolve at the boiling point of n-hexane at 68° C. and has no change in state at this temperature, this could be a reason why it does not react with P2O5 in n-hexane.
- 2. Study on Reaction Temperature
- Pentaerythritol does not react with P 2O5 in toluene solvent at a temperature lower than 70° C. under traditional stirring process. When the temperature increases to 90° C., pentaerythritol can undergo a phosphate esterification reaction. The reaction time is about 10 hours. When the temperature rises to 105° C., the reaction time can be reduced to 6 hours.
- 3. Effects of the Particle Size of Pentaerythritol
- The reaction yield and purity can be increased when, prior to the reaction, pentaerythritol is ground in toluene in a ball mill.
- 4. Ball Mill Process
- Based on the above studies 1˜3, the key factors affecting the method of the present invention include: heating of the solvent, material with a fine particle size, and complete mixing in the reaction. Therefore, a ball mill is considered as a reactor to achieve a complete grinding, mixing and thermal insulation in the reaction. A suitable reaction time is 4-20 hours.
- 5. Formation of Phosphoric Acid in the Reaction
- When 2 moles of pentaerythritol reacts with 1.5 mole of P 2O5, 1 mole of bis-(pentaerythritol phosphate) phosphoric acid and 3.5 moles of water will be generated. Since 3 moles of water will react with 1 mole of P2O5 to from 2 moles of phosphoric acid, and a consumption of P2O5 occurs. Therefore, an excessive amount of P2O5 should be used for all the pentaerythritol phosphate alcohol to be converted to bis-(pentaerythritol phosphate) phosphoric acid. A suitable mole ratio of pentaerythritol to P2O5 is 4:3 to 1:2.
- The reaction between melamine and bis-(pentaerythritol phosphate) phosphoric acid according to the present invention can be carried out in said ball mill or a conventional mechanical agitation reactor, preferably in a ball mill. The reaction can be carried out using acetonitrile or water as the solvent. According to the present invention, when the conventional mechanical mixing is used and acetonitrile is used as a solvent, the reaction can be completed in 6 hours by reflux. In the ball mill process where acetonitrile which is pre-heated to 80° C. is used, the reaction time is 7.5 hours. In the ball mill process, if toluene is still used as a solvent in the reaction for forming melamine salt after the preparation of bis-(pentaerythritol phosphate) phosphoric acid, the result is poor. After the completion of the preparation of bis-(pentaerythritol phosphate) phosphoric acid in the ball mill process, if the original solvent (400 ml) is retained and another 100 ml of acetonitrile, which is pre-heated to 80° C., is added as a solvent in the reaction for forming melamine salt, the reaction can be carried out smoothly and the reaction time is also 7.5 hours. Furthermore, if the remaining solvent is poured out and boiling water is added as a solvent in the reaction for forming melamine salt, the reaction time can be greatly reduced to 15-60 minutes. The obtained melamine salt of bis-(pentaerythritol phosphate) phosphoric acid has a good heat resistance, only about 10˜20% of which will be decomposed at 200˜300° C., and about 40% of which will remain at a temperature exceeding 600° C.
- The present invention uses P 2O5 to replace POCl3, and a mechanochemical synthesis process to overcome lack of a suitable solvent. Thus, the present invention has the following advantages: no formation of hydrochloric acid, no waste solution, environmentally friendly, without the need of heating in the reaction, high yield, increased purity, and capability of recycling solvent.
- The reaction formulas involved in the following Examples are shown in the following:
- Since P 2O5 will be consumed by the 7/2 moles of water simultaneously formed during the reaction, an excessive amount of P2O5 is needed in the reaction. Therefore, a small amount of H3PO4 will be also formed together with the product as shown in the following reaction:
- P2O5+3H2O→2H3PO4
- Since P 2O5 is very hygroscopic, the feeding must be carried out by using an enclosed feeding device for solid feed.
- A ball mill reactor with one liter capacity was used and ceramic balls with a diameter of 2 cm were used.
- 13.6 g (0.1 mol) of pentaerythritol and 18.88 g (0.133mol) of P 2O5were used. 400 ml of toluene was used and was pre-heated to 90˜100° C. After drying, the ball mill reactor was added with the pre-heated solvent, and sequentially added with pentaerythritol, P2O5, and 0.4 g of MgCl2, followed by ceramic balls. The ball mill reactor was then closed and rotated. The reaction was carried out for 6 hours. After the reaction, the liquid portion in the ball mill reactor was poured out, and the remaining product mixture was subjected to a reduced pressure to evaporate the solvent contained therein. 31P-NMR spectrum of the product mixture was taken and the integration areas of bis-(pentaerythritol phosphate) phosphoric acid (b-PEPAP) and phosphoric acid therein were calculated, thereby obtaining the phosphor content ratios thereof, wherein the relative phosphor content ratio of b-PEPAP to phosphoric value is 56 to 44. The phosphor content ratio was used to calculate the purity of b-PEPAP in the product mixture, which is 65 wt %.
- 31P-NMR was used to identify the main components in the product mixture obtained by the mechanochemical synthesis ball mill process in Example 1, wherein DMSO d6 was used as a solvent. The results indicate that the resonance at 0.4 ppm was phosphoric acid, −0.3 ppm was P—OH, −6.4 ppm was P on the bicyclo ring (pentaerythritol phosphate alcohol, as shown in Example 1 of EP 0 578 318 A1).
- The product mixture of Example 1 was retained in the ball mill reactor, after the liquid portion was poured out. 21 g (0.166 mol) of melamine was poured into the ball mill, and 300 ml of acetonitrile which was pre-heated to 80° C. was added. The ball mill reactor was closed and rotated for 6 hours. 31P-NMR spectrum of a sample of the reaction solution taken from the ball mill reactor showed no existence of 31p peak, which indicated that b-PEPAP and phosphoric acid were all consumed. The product b-PEPAP.MEL and the by-product melamine salt of phosphoric acid were all insoluble in acetonitrile solvent. The reaction was completed with a conversion rate of 100%.
- The procedures in Example 2 were repeated except that the liquid portion of the reaction mixture in the ball mill reactor was not poured out, 100 ml of acetonitrile which was pre-heated to 80° C. was added instead of 300 ml, and the ball mill reactor was for 7.5 hours. The conversion rate was 100%.
- The procedures in Example 2 were repeated except that 350 ml of pre-heated boiling water was added instead of acetonitrile, and the ball mill reactor was rotated for 15 minutes only. 31P-NMR spectrum of a sample of the reaction solution taken from the ball mill reactor showed no existence of 31P peak. The reaction was completed with a conversion rate of 100%.
- The melamine salt of bis-(pentaerythritol phosphate) phosphoric acid obtained in Example 2 to Example 4 had an average particle size of 6-8 μm, and the particle size distributions thereof showed that 91% of the particles were smaller than 14.4 μm. Their IR spectrums were were substantially the same and contained the following major characteristic absorption wavelength:
- 900˜1060 (broad): P—O—CH 2R (Vibration)
- 1164˜1185 (strong): P═O (Vibration)
- 1430˜1548 (medium): primary amine salt, bending
- 1650 (wide, strong): O═P—OH
- 3100 (strong): amine salt, primary
- 3300 (medium): primary amine
Claims (11)
1. A method for preparing a melamine salt of bis-(pentaerythritol phosphate) phosphoric acid by a mechanochemical synthesis, which comprises the following steps: (a) ball milling a mixture comprising P2O5, pentaerythritol, an alkyl benzene having one or two C1-C5 alkyl groups, and a metal halide catalyst in a ball mill reactor at a temperature of room temperature to 150° C. to form bis-(pentaerythritol phosphate) phosphoric acid; and (b) ball milling or mechanically mixing a mixture comprising melamine, bis-(pentaerythritol phosphate) phosphoric acid and a solvent at room temperature to 100° C., wherein said solvent is water, acetonitrile, or a mixture of the solvent in step (a) with acetonitrile.
2. The method as claimed in claim 1 , wherein said alkyl benzene is toluene, and said metal halide catalyst has a chemical formula of MX2, wherein M is Mg, Zn or Al, and X is Cl or Br.
3. The method as claimed in claim 2 , wherein said metal halide catalyst is MgCl2.
4. The method as claimed in claim 1 , wherein a molar ratio of pentaerythritol to P2O5 in said mixture of Step (a) is 4:3 to 1:2.
5. The method as claimed in claim 1 , wherein a weight ratio of said catalyst to pentaerythritol in said mixture of Step (a) is 1:99 to 5:95.
6. The method as claimed in claim 1 , wherein said ball milling in Step (a) is carried out for 4-20 hours.
7. The method as claimed in claim 1 , wherein said temperature in Step (a) is 90-105° C.
8. The method as claimed in claim 2 , wherein said toluene in Step (a) is pre-heated to a temperature of 90-100° C. prior to being added to said ball mill reactor; and said ball milling in Step (a) is carried out without heating.
9. The method as claimed in claim 1 , wherein said solvent in Step (b) is pre-heated to 50-100° C., and said mixture in step (b) is ball milled in said ball mill reactor without heating.
10. The method as claimed in claim 9 , wherein said solvent is a mixture of toluene with acetonitrile pre-heated to 50-80° C., acetonitrile pre-heated to 80° C., or boiling water.
11. The method as claimed in claim 10 , wherein said solvent is boiling water.
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| TW091124590A TWI221474B (en) | 2002-10-23 | 2002-10-23 | Method for preparing melamine salt of bis-(pentaerythritol phosphate) phosphoric acid |
| TW91124590 | 2002-10-23 |
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| US20060188512A1 (en) * | 2003-02-01 | 2006-08-24 | Ted Yednock | Active immunization to generate antibodies to solble a-beta |
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| US6833467B2 (en) * | 2002-11-12 | 2004-12-21 | Chung-Shan Institute Of Science & Technology | Method for preparing pentaerythritol phosphate alcohol by mechanochemical synthesis |
| US7250509B1 (en) * | 2006-05-31 | 2007-07-31 | Chung Shan Institute Of Science And Technology | Method for preparing melamine salt of pentaerypolyol phosphoric acid |
| TW200840815A (en) * | 2007-04-13 | 2008-10-16 | Chang Chun Plastics Co Ltd | Method for preparing melamine salt of bis(pentaerythritol phosphate)phosphoric acid |
| CN101289465B (en) * | 2007-04-19 | 2011-08-03 | 长春人造树脂厂股份有限公司 | Process for preparing di(phosphoric acid pentaerythrite ester)phosphoric acid melamine salts |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4478998A (en) * | 1983-05-23 | 1984-10-23 | Borg-Warner Chemicals, Inc. | Process for preparing amine salts of phosphoric acids |
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| US4478998A (en) * | 1983-05-23 | 1984-10-23 | Borg-Warner Chemicals, Inc. | Process for preparing amine salts of phosphoric acids |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060188512A1 (en) * | 2003-02-01 | 2006-08-24 | Ted Yednock | Active immunization to generate antibodies to solble a-beta |
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